Interactive Tool
Board Foot Calculator
Use this board foot calculator to estimate lumber volume, add realistic waste, account for milling loss, and get a better feel for what your project may actually require before you buy wood. It works well for furniture parts, cutting boards, glue-ups, shelves, panels, and general shop planning.
What this helps with
Figuring out how much lumber you need before heading to the hardwood dealer, pricing a build, or realizing too late that your parts list did not include waste, trimming, or bad grain.
Best use
Project planning, rough lumber buying, cost estimates, cutting board glue-ups, shelves, tables, panels, and batch builds.
Keep in mind
The formula is simple, but real projects need extra room for defects, milling, mistakes, and grain selection. This tool helps cover that reality.
Quick answer
A board foot is 144 cubic inches of lumber. The base formula is simple, but most woodworkers should buy more than the bare minimum. In real shops, the useful number is usually your calculated board footage plus waste, milling loss, and a little breathing room.
Calculator
Enter actual thickness in inches.
Enter actual width in inches.
Enter length in inches.
How many identical pieces you need.
Optional, but useful for quick cost checks.
A practical starting point for basic buying margin.
Finished target thickness in inches.
Final project width in inches.
Final project length in inches.
Number of finished pieces.
Optional for estimating lumber cost.
Covers trimming, defects, grain choice, and mistakes.
Use this if you hate coming up short.
Average width of the rough boards you expect to buy.
Average usable length in inches after cutting around defects.
How much finished material your project truly needs.
For rough lumber cost estimating.
Captures repeated cuts and trim waste.
What the result means
The calculator gives you a base board footage number plus a more realistic purchase estimate. That second number is usually the one that matters most in the real world.
Base board feet
This is the pure math from your dimensions before real-world shop losses are added.
Recommended purchase
This adds waste, milling, trimming, defects, and a practical safety margin depending on the mode you are using.
How to use this tool well
- Start with your finished dimensions or your actual part sizes.
- Use the simple mode for quick math, the project mode for realistic shopping, and the real shop mode when rough lumber and milling losses are part of the job.
- Enter a price per board foot if you want a rough material cost before buying.
- Add enough allowance for defects, trimming, and grain choice; especially for visible furniture parts.
- When in doubt, buy a little extra. A second trip is usually more expensive than one extra board.
When woodworkers usually come up short
Ignoring milling loss
Rough lumber rarely ends at the same thickness and width you bought on paper.
Buying only exact footage
The formula does not account for defects, grain selection, or mistakes.
Forgetting trim waste
Crosscuts, kerf, and squaring ends quietly eat up material.
FAQ
What is a board foot?
A board foot is a volume measurement equal to 144 cubic inches of lumber. One common way to picture it is 1 inch thick, 12 inches wide, and 12 inches long.
How do I calculate board feet from inches?
Multiply thickness by width by length, all in inches, then divide by 144.
Why does rough lumber need more allowance?
Because you usually lose some material to flattening, jointing, planing, trimming, cutting around defects, and selecting better grain.
How much extra lumber should I buy?
It depends on the project, but many woodworkers add around 10% to 20% for simpler work and more for figured stock, rough lumber, matched grain, or high-precision furniture parts.
Can I use this for cutting boards?
Yes. It is especially useful for cutting boards and glue-ups because those builds often need extra material for flattening, trimming, and dialing in a nicer final look.
Bottom line
The board foot formula is easy. Buying the right amount of wood is the hard part. Use the clean number as your baseline, then use the real-world estimate so your project survives milling, trimming, and the normal chaos of a woodworking shop.